The present invention relates to molded adsorbents, and more specifically to molded articles comprising adsorbents and a small amount of binder and having high strength and large adsorptive capacity.
Various molding processes are known for the purpose of producing molded articles comprising adsorbents. Most of the processes apply to activated carbon as an adsorbent and comprise using coal tar or pitch as a binder and molding the mixture. Molded adsorbents obtained by these processes however have markedly decreased absorptive capacity since the binder covers the surface of activated carbon. It therefore becomes necessary to first mold a mixture of the binder with a raw material of activated carbon and then submit the molded article to activation treatment to obtain activated carbon. Although this is a complex process and has a drawback that the finished molded products obtained by this process tend to be deformed, these products have excellent mechanical properties and are hence frequently used for honeycomb-shaped adsorbents having complex structures.
A process comprising the use of a latex as binder has, in recent years, also been applied to various adsorbents. This process has an advantage in that granules or particles of the adsorbent used can be molded to directly give a usable molded adsorbent. However, it has been pointed out that the molded adsorbent thus prepared have some problems of considerable reduction in the absorptive capacity and in that they are relatively soft and have not so high mechanical properties.
Conventional deodoring units used for air cleaners and air conditioners are generally so constructed that a filter previously formed of an adsorbent is fitted in the front of the body, through which filter air is passed by a fan to be deodored. This system has, in the case where a large amount of air is flown therethrough, drawbacks of large pressure loss, high noise level caused by the motor and fan used and high electricity cost.
If a fan itself can be molded from a mixture containing an adsorbent, to be provided with both air blowing function and deodoring function, there will be provided an deodoring apparatus requiring no stationary deodoring unit and causing only small pressure loss, low noise and low power consumption.
Although attempts have been made to mold an adsorbent into a fan shape, no deodoring fans withstanding high-speed rotation and having large absorptive capacity have ever been obtained. An increased amount of a binder is required for obtaining a fan with high strength, whereby the absorptive capacity decreased significantly and such a fan can hardly be put in practical use. Furthermore, water-soluble binder such as carboxymethylcellulose have been used in most of the attempts for this purpose, which causes the obtained blades for fans to be soft, being unable to withstand high-speed revolution, and to have only small adsorptive capacity.